Handle PortNotFoundClient exception when getting ports

There could be a race between deleting an instance and retrieving its
port groups from Neutron. In this case PortNotFoundClient is raised and
it can be safely ignored.

Change-Id: I31c9ea8628c6f3985f8e9118d9687bbfb8789b68
Closes-Bug: #1767058

nova/network/security_group/neutron_driver.py

@@ -332,7 +332,13 @@ class SecurityGroupAPI(security_group_base.SecurityGroupBase):
         ports = []
         for ids in _chunk_by_ids(servers, MAX_SEARCH_IDS):
             search_opts = {'device_id': ids}
+            try:
                 ports.extend(neutron.list_ports(**search_opts).get('ports'))
+            except n_exc.PortNotFoundClient:
+                # There could be a race between deleting an instance and
+                # retrieving its port groups from Neutron. In this case
+                # PortNotFoundClient is raised and it can be safely ignored
+                LOG.debug("Port not found for device with id %s", ids)
 
         return ports
 

nova/tests/unit/network/security_group/test_neutron_driver.py

@@ -305,6 +305,19 @@ class TestNeutronDriver(test.NoDBTestCase):
         self.assertEqual(sorted([sg1_id, sg2_id]),
             sorted(self.mocked_client.list_security_groups.call_args[1]['id']))
 
+    def test_instances_security_group_bindings_port_not_found(self):
+        server_id = 'c5a20e8d-c4b0-47cf-9dca-ebe4f758acb1'
+        servers = [{'id': server_id}]
+
+        self.mocked_client.list_ports.side_effect = n_exc.PortNotFoundClient()
+
+        sg_api = neutron_driver.SecurityGroupAPI()
+        result = sg_api.get_instances_security_groups_bindings(
+                                  self.context, servers)
+        self.mocked_client.list_ports.assert_called_once_with(
+            device_id=[server_id])
+        self.assertEqual({}, result)
+
     def _test_instances_security_group_bindings_scale(self, num_servers):
         max_query = 150
         sg1_id = '2f7ce969-1a73-4ef9-bbd6-c9a91780ecd4'